Exam Study Notes for Stat 201/204

Exam Overview

• Course: Stat 201/204

• Exam Name: Fall 2025 Practice Exam 1

• Recitation Number: 9/19/2025

• Time Limit: 120 Minutes

• Total Pages: 6 (including cover page)

• Total Problems: 4

• Materials Allowed:

  • One two-sided 4” x 6” note card

  • A calculator

• Materials Not Allowed:

  • Any other material

Exam Instructions

• Show Your Work:

  • All steps of calculations must be shown for full credit.

  • Check answers with calculator but must show every step.

• Organization:

  • Work should be organized neatly and coherently; disorganized work receives little credit.

• Prohibition:

  • Do not write in the provided table on the right of the page.

Problem Distribution and Scoring

• Problem 1: 10 Points

• Problem 2: 10 Points

• Problem 3: 10 Points

• Problem 4: 10 Points

• Total Points: 40

  Problem 1: Dr. Pepper Can Analysis

• Context:

  • Jackson, a Dr. Pepper enthusiast, is concerned about the average fill volume of his cans.

  • Sampled 25 cans, average volume found: 11.78 ounces, Standard deviation: 0.25 ounces.

Part (a) - Standard Deviation Type

• Question: Which of the following did Jackson find?

  • (i) Statistic

  • (ii) Parameter

  • (iii) Boxplot

  • (iv) Nominal

  • (v) None of these

• Correct Answer: (i) Statistic

Part (b) - Standard Deviation Symbol

• Question: What is the appropriate symbol for 0.25 ounces?

  • (i) s

  • (ii) s²

  • (iii) µ

  • (iv) ψ⃗

  • (v) None of these

• Correct Answer: (i) s

Part (c) - Measure of Center

• Context: Data from Jackson is skewed due to overfill limitation.

• Question: What would have been a better measure of center?

  • (i) Median

  • (ii) Average

  • (iii) Weighted Mean

  • (iv) Variance

  • (v) IQR

• Correct Answer: (i) Median

Part (d) - Median Percentile

• Context: Jackson found the median = 11.85 ounces.

• Question: What percentile is the median?

  • (i) 25th

  • (ii) 50th

  • (iii) 75th

  • (iv) 76th

  • (v) None of these

• Correct Answer: (ii) 50th

Part (e) - Visual Inspection of Data

• Question: What plots would be appropriate for data inspection?

  • (i) Stem and Leaf Plot

  • (ii) Bar Graph

  • (iii) Histogram

  • (iv) Pie Chart

  • (v) Scatterplot

• Correct Answers: (i) Stem and Leaf Plot, (iii) Histogram

Problem 2: CSU Student Study

• Context: Researchers study academic performance among 30,000 enrolled students, sampling 500 for various data collection.

• Collecting Data About Each Student:

  • Variables Collected:

  • Class standing (Freshman, Sophomore, Junior, Senior)

  • Number of credit hours enrolled

  • Favorite study location (options: Library, Coffee Shop, Dorm Room, Other)

  • GPA (on a 4.0 scale)

Part (a) - Population and Sample

• Task: Identify the population and the sample in this study.

• Population: All 30,000 enrolled students.

• Sample: 500 selected students.

Part (b) - Identifying Quantitative Variables

• Question: Which of the following are quantitative?

  • (i) Class Standing

  • (ii) Number of Credit Hours

  • (iii) Study Location

  • (iv) GPA

• Correct Answers: (ii) Number of Credit Hours, (iv) GPA

Part (c) - Qualitative and Ordinal Variables

• Question: Which of the following are qualitative and ordinal?

  • (i) Class Standing

  • (ii) Number of Credit Hours

  • (iii) Study Location

  • (iv) GPA

• Correct Answer: (i) Class Standing

Context of Two Studies

• Study 1:

  • 500 students report average sleep hours, then compare with GPAs.

• Study 2:

  • Randomly assign 500 students to either a sleep group (8 hours) or control group (usual sleep), then compare GPAs.

Part (d) - Observational Study Identification

• Question: Which study is observational?

• Correct Answer: Study 1

Part (e) - Identifying Variables

• Question: In Study 1, identify predictor and response variables.

• Predictor Variable: Self-reported sleep hours.

• Response Variable: GPA.

Problem 3: YouTube Viewing Habits

• Context: 12 CSU students surveyed on daily hours spent watching LeBron James videos. Responses: 10, 12, 13, 13, 2, 15, 4, 5, 9, 7, 12.5, 14

Part (a) - Fill Frequency Table

• Task: Complete frequency for ranges below:

  • Group: 0 ≤ Hours ≤ 4

  • Group: 4 < Hours ≤ 8

  • Group: 8 < Hours ≤ 12

  • Group: 12 < Hours ≤ 16

Part (b) - Distribution Description

• Question: Which best describes the distribution of responses?

  • (i) Normal

  • (ii) Positively skewed

  • (iii) Negatively skewed

  • (iv) Symmetric

  • (v) None of these

• Correct Answer: (ii) Positively skewed

Part (c) - Percentage Calculation

• Question: Calculate the percentage of responses more than 2 and at most 13.

Part (d) - Mode Calculation

• Question: What is the mode of the distribution?

• Correct Answer: 13 (since it appears most frequently)

Problem 4: Super Bowl Halftime Show

• Context: Viewership of halftime shows from 2020 to 2025 (in millions): 103.0, 96.7, 103.4, 118.7, 129.3, 133.5

Part (a) - Mean Calculation

• Task: Calculate the mean viewership from 2020 to 2025.

Part (b) - Median Calculation

• Task: Calculate the median viewership from 2020 to 2025.

Part (c) - Sample Variance Calculation

• Task: Calculate sample variance from 2020 to 2025.

Scratch Paper

• Note: Do not place final answers on the scratch paper provided on the last page.